1. Field of the Invention
This invention relates to buffered digestive enzymes and salts of bile acids, and more particularly salts of ursodeoxycholic acid compositions for ingestion by a mammal, a process for preparing said compositions, and a method for treating digestive disorders, pancreatic enzyme insufficiency, impaired liver function, pancreatitis, cystic fibrosis, regulating dietary cholesterol absorption and for dissolving gallstones by administering said compositions to a mammal in need of such treatment.
2. Reported Developments
It is known in the prior art that pancreatic enzymes administered to mammals can remedy enzyme deficiency caused by various diseased conditions of the pancreas, such as cystic fibrosis, pancreatitis, pancreatic enzyme deficiency and old age. Oral administration of compositions containing these enzymes requires the presence of certain conditions in order for them to be safe and effective as will be described hereunder.
Pancreatic enzymes produced by the patient's pancreas are released into the duodenum, the pH of which is close to neutral or slightly alkaline. Under these pH conditions the enzymes are active and digestion of the food by the enzymes proceeds normally in the upper segment of the intestine. However, when pancreatic enzymes are administered exogenously to the patient, the gastric conditions in the stomach, namely the presence of acid and pepsin, will irreversibly inactive the enzymes. Therefore, orally administered enzymes must be protected against gastric inactivation so that they remain intact during their transit through the stomach into the duodenum.
Once the exogenously introduced enzymes reach the duodenum, another requirement must be satisfied: the enzymes must be released from their protective environment and intimately mixed with the food transferred from the stomach to effect digestion at a neutral to slightly alkaline condition.
U.S. Pat. No. 4,079,125 incorporated herein by reference, addresses these requirements in a composition containing these enzymes and provides preparative methods for making the compositions. The compositions provided by said patent comprise: an enzyme concentrate in a binder selected from the group consisting of polyvinylpyrrolidone, microcrystalline cellulose, cellulose acetate phthalate, methylcellulose and alginic acid; a stabilizer selected from the group consisting of calcium carbonate, polyvinylpyrrolidone, cellulose acetate phthalate, methylcellulose, starch and modified starches and alginic acid; a disintegrant selected from the group consisting of citric acid, sodium carbonate, sodium bicarbonate, calcium carbonate, starch and modified starches and alginic acid; said mixture is coated with a non-porous, pharmaceutically acceptable enteric coating polymer which is insoluble in the pH range of from about 1.5 to about 5 normally present in gastric fluids, and soluble at a pH of from about 6 to about 9, the normal pH range for mammalian intestinal fluids.
The orally administered composition passes through the stomach while being protected against the acidic environment by its acid-insoluble coating which then disintegrates in the neutral to basic environment of the upper intestine releasing the enzymes from the composition. The process of making the compositions includes the provision of using a solvent and avoiding the presence of water in the blending step of the enzyme/binder/disintegrant, since it is believed that water deactivates some of the enzymes.
Contrary to the teaching of U.S. Pat. No. 4,079,125, it has now been discovered that the complete exclusion of the water (anhydrous condition) during the process of preparing the buffered enzymes/salts of ursodeoxycholic acid compositions in the form of microtablets and microspheres, leads to products that are extremely friable, tend to crumble into pieces upon drying in a fluidized bed dryer or conventional coating pan and disintegrate upon initiation of the polymer coating step. This results in large amounts of dust and agglomeration of the beads into multiplets during the process as well as improper doses of the enzymes upon administration to the patient when quality control fails adequately to sort out and discard rejects.
It is also known that ursodeoxycholic acid (hereinafter UDCA or bile acid) is capable of augmenting liver function, dissolving gallstones and improving the nutritional state of patients having hepatobiliary complications associated with cystic fibrosis. See for example, Ursodeoxycholic Acid Dissolution of Gallstones in Cystic Fibrosis, Sahl, B., Howat, J., Webb, K., Thorax, 43:490-1 (1988); Effects of Ursodeoxycholic Acid Therapy for Liver Disease Associated with Cystic Fibrosis, Colombo, C., Setcheil, K. D., Podda, M., Crosignani, A., Roda A., Curcio, L., Ronchi, M. and Giunta, A., The Journal of Pediatrics, 117:482-489 (1990); Effects of Ursodeoxycholic Acid Treatment on Nutrition and Liver Function in Patients with Cystic Fibrosis and Longstanding Cholestasis. Cotting, J., Lentze, M. J. and Reichen, J., Gut 31:918-921 (1990). Also, UDCA has recently gained acceptance as an effective therapeutic modality to dissolve small to medium size cholesterol gallstones in gallstone afflicted patients. See for example, The Effect of High and Low Doses of Ursodeoxycholic Acid on Gallstone Dissolution in Humans, Salen, G., Colalillo, A., Verga, D., Bagan, E., Tint, G. S. and Shefer, S., Gastro,, 78:1412-1418 ( 1980); Ursodeoxycholic Acid: A Clinical Trial of a Safe and Effective Agent for Dissolving Cholesterol Gallstones, Tint, G. S., Salen, G., Colalillo, A., Graber, D., Verga, D. Speck, J. and Shefer, S., Annals of Internal Medicine, 91:1007-1018 (1986); Clinical Perspective on the Treatment of Gallstones with Ursodeoxycholic Acid, Salen, G., J. Clin. Gastroenterology, 10 (Suppl. 2):S12-17 (1988); Nonsurgical Treatment of Gallstones, Salen, G. and Tint, G. S., New England J. Med, 320:665-66 (1989); and Reducing Cholesterol Levels, Weigand, A. H., U.S. Pat. No. 3,859,437. The recommended dosage is 10 to 15 mg/kg of body weight. In some patients much higher dosages (for example, about 30 mg/kg of body weight) are required to achieve limited benefits. However, in some patients undesirable side effects (such as, severe diarrhea) seriously limit the use of this drug. The reasons for this wide variation of dosage requirements for therapeutic effectiveness and associated side effects are not completely understood. One hypothesis is that the free acidic form of UDCA is only partially neutralized in the upper intestine to its sodium salt form due to deficiencies in bicarbonate in some of the patients. The residual free acidic (insoluble) form of UDCA is poorly absorbed from the intestine, and a good portion of the administered dosage is excreted intact with feces. When a higher dosage of the acidic form of UDCA is administered to the patient, a large portion of it is neutralized in the distal parts of the intestine which in turn induces diarrhea, a highly undesirable side effect. Also, if the acidic form of UDCA is to be converted into its salt form in the duodenum, it will temporarily exhaust the buffering capacity of the duodenum and it will render the upper intestine partially acidic. The acidic pH impedes the function of the pancreatic enzymes and UDCA cannot emulsify fats and facilitate the hydrolysis of lipids. Furthermore, the many therapeutic benefits derived from the salt forms of UDCA cannot be realized. It should then follow, accordingly, that the salt forms of UDCA should be administered to patients in need of UDCA. U.S. Pat. No. 3,859,437 recommends the administration of a "small but effective amount, sufficient to effect a reduction in the cholesterol level of said human being of the compound 3.alpha. 7.beta.-dihydroxy-5.beta.-cholanic acid (UDCA) and the non-toxic pharmaceutically acceptable salts thereof". However, administering the salt form of UDCA to patients has no advantage over the acidic form of UDCA and does not accomplish the desired results since the salt form of UDCA is converted back to the insoluble acidic form of UDCA by gastric acidity. Furthermore, the salt forms, i.e., sodium or potassium, of UDCA are extremely bitter-tasting, and in most patients cause esophageal reflux, nausea and vomiting. Because of these highly undesirable organoleptic and gastric side effects, the salt forms of UDCA has not gained therapeutic utility in the treatment of biliary diseases.
Pancreatic enzymes and salts of UDCA complement one another in the digestive system of a mammal. A dietary supplement containing both the enzymes and salts of UDCA would provide in a convenient predetermined dose the remedy needed to treat the above-described diseased states. However, the acidic form of UDCA is incompatible with pancreatic enzymes. Pancreatic enzymes/UDCA compositions have a pH of about 5 to 5.5. Under these acidic conditions most pancreatic enzymes show a low biological activity of about 10% to 40%. Lipase is especially affected by the low pH for the reasons that: UDCA is only sparingly soluble in aqueous media and is inefficient to emulsify fats; and the acidic UDCA inactivates lipase since lipase requires a basic pH for biological activity.
Pancreatic enzymes/UDCA containing compositions also lack sufficient shelf-life due to the denaturing and detergent effects of UDCA on the pancreatic enzymes. Because of these incompatibilities between UDCA and pancreatic enzymes the many benefits derivable from their combinations could not be realized by the prior art.
It has now been discovered that the problems associated individually with enteric coated microtablets and microspheres containing pancreatic enzymes and compositions containing UDCA, may be overcome in a dietary supplement containing both the pancreatic enzymes and a salt of UDCA. In accordance with the discovery, UDCA is first converted to a pharmaceutically acceptable salt, such as the sodium or potassium salt and then used in a combination with pancreatic enzymes in a composition. Such salts are highly effective to emulsify fats and lipids at a basic pH and facilitate the hydrolysis of the emulsified fat globules. As a result, fat digestion is greatly enhanced. The salts are also more effective than the insoluble acidic form of UDCA to lyse mucus which blocks the intestinal surfaces and prevents absorption of metabolites that results in poor nutrition in cystic fibrosis children.
Pancreatic enzymes then are combined with a salt of UDCA and buffered with a biologically compatible, pharmaceutically acceptable buffer that prevents deactivation of the enzymes and preserves the natural biological activities of both the buffered enzymes and the salt of UDCA. The pancreatic enzymes/salt of UDCA composition can be prepared into microtablets and microspheres in the presence of moisture without inactivation of the enzymes/bile salt composition thereby resulting in products that do not crumble upon drying or disintegrate upon initiation of the polymer coating procedure. The bitter taste and associated gastric disadvantages of UDCA salts are also eliminated by the polymer coating which prevents solubilization of the product in the mouth and stomach of the patient.
Still further, it has been discovered that microspheres in the range of 10 to 80 mesh size (about 2.0 to 0.177 mm range) can be prepared utilizing bile salts as seeds to build up the microspheres. Such small particle size microspheres are especially beneficial for use to treat pancreatic enzymes/bile salt deficiencies in cystic fibrosis children.